Process for degreasing metallic articles



June 5, 1934. S V E; 1,961,867

PROCESS FOR DEGREASING METALLIC ARTICLES Original Filed Dec. 16-. 1926 45 chlorethylene) ii atentecl June 5, 193 4 UNITED STATES PROCESS FOR. DEGREASING METALLIC ARTICLES Joseph Savage, Runcorn, England, assignor to The Castner Kellner Alkali Company Limited,

Runcorn,

England, a British company Original application December 16,1926, Serial No. 155,324. 2, 1931, Serial No. June 23, 1926 4 Claims.

tained with a smaller quantity of solvent.

The present invention therefore consists in the process of degreasing metallic articles comprising subjecting the cold articles to the warm vapour of a grease solvent to condense such vapour on the surface of the articles and dissolve the grease thereon and allowing the condensed solvent and grease dissolved therein to drain away from the articles.

It has been known to extract animal and vegetable products with condensed vapours of oil solvents, but metallic articles are radically different from such products.

They are non-absorbent so that any liquid condensed thereon readily runs off. They also have a comparatively small ratio of area to mass or volume as compared with vegetable substances so that only a very small proportionate amount of liquid is retained mechanically on their surfaces. Further, they have a relatively high specific heat so that they are capable of con-.

densing considerable volumes of solvent before reaching the temperature of the solvent vapours.

Using trichlorethylene having a boiling point of 853 C. and a latent heat of vaporization at that temperature of 239 calories per gram-(Internat. Crit. Tables Vol. V page 136) and a density of 1.46 (Handbook of Chemistry and Physics, 11th edition, page 385) and steel castings having a specific heat of 0.113 and a density of around 7.60 (Handbook of C. 8: P. P. 147).

it can be readily calculated that 100 volumes of castings will condense 16 volumes of trichlorethylene in being heated from- 20 C. (room temperature) to 85.'7 C. (boiling point of tri- Obviously 16 volumes of solvent is far in excess of what the castings will retain mechanically upon their surface. By far the larger part will drain off and carry with it the oil and grease dissolved therein.

Such condensation of vapors is especially advantageous as it takes place not only on the upper surfaces ofthe castings but also on the under surfaces and in corners not reached by a. spray of solvent-and which would otherwise be reached only by total immersion of the cast- Divided and this application July 548,465. In Great Britain ings in a bath of the solvent. The latter method obviously involves the evaporation of very large quantities of solvent whereas the present method is extremely economical in that the evaporation of relatively small amounts of solvent are sumcient to remove the grease.

In Fig. l of the accompanying drawing the dry degreaser shown in sectional elevation consists of a metallic vessel 1 of about the size and shape of an ordinary bucket, with an extension 7 at its lower end.

Inside this there hangs a perforated frustroconical basket 2 from a small ledge 8.

3 and 4 are water cooling coils, 4 being in the detachable lid while 3 is situated at the top of the extension '7, just below the perforated basket 2, perforated as shown at 11.

6 Ba valve for the removal of oil or greasy matter. V

The lid 5 has a horizontal flange 9 and a vertical flange 10 engaging with similar flanges on the walls of the casing.

In operation the material to be degreased is placed in the basket and the bottom of the vessel is filled with a volatile non-inflammable solvent e. g. trichlorethylene. The lid is placed in position. Heat is applied to the base of the vessel and cold water is run through coil 4. The solvent distils from 7 and is condensed on the material to be degreased, excess vapours being condensed by 4. The condensed liquid drops from the coil 4 and runs down over the material to be degreased on its way back to be re-volatilized. It is desirable to efiect uniform distribution of the falling liquid and this may be done by suitably shaping or disposing the cooling coil or by providing flanges or points thereon from which the liquid may drip.

When it is desired to remove the perforated basket water is allowed to flow through the bottomcoil to condense the vapour in the apparatus. I

When the solvent is heavily contaminated with oil the perforated basket may be replaced by an imperforate container e. g. a small bucket and the apparatus then used as a rectifier so that clean solvent collects in the basket, while the residual oil may be drawn off from below.

I declare that what I claim is:--

1. A process for degreasing metallic articles by means of a volatile solvent and without undue loss of solvent, which process is adapted to be carried out in a single open-topped vessel having a lid adapted to be opened to permit insertion of articles to be degreased or removal of degreased articles, and adapted to be closed during the degreasing treatment, which articles during the degreasing operations are supported between upper and lower cooling coils in said vessel, said process comprising initially heating the solvent and causing the vapors to pass upwardly into contact with the surface of the cold articles undergoing treatment, whereby part of the vapors are condensed on the surface of the articles, further condensing the vapors by cooling the same above the articles undergoing treatment, and causing the condensate to pass downwardly through the said articles to assist in the cleaning operation, then substantially completely condensing any vapors remaining below the articles undergoing treatment, arid allowing the condensed solvent and grease dissolved therein to drain away before opening the lid to remove said articles from the vessel, whereby loss of solvent vapors is avoided.

2. The process of degreasing metallic articles comprising placing such articles inside a combined still and container from which they may be readily removed, and subjecting the cold articles while substantially free from water to the warm vapor of a grease solvent heavier than water to condense such vapour on the surface of the articles and dissolve the grease thereon, and allowing the condensed solvent and grease dissolved therein to drain away from the articles into the body of liquid in said combined still and container from which the vapour is distilled,

whereupon the articles are dried without bringing them in contact with water.

3. The process of degreasing metallic articles comprising subjecting the cold articles while in a degreasing vessel to the warm vapour of a volatile grease solvent to condense such vapour on the surface of the articles and dissolve the grease thereon, allowing the condensed solvent and grease dissolved therein to drain away from the articles, and condensing vapor inside said vessel during and after degreasing by supplying cooling fluid to conduits inside the degreasing vessel.

4. A process for degreasing metallic articles by means of a volatile grease solvent without undue loss of solvent, which process is adapted to be carried out in a single open-topped vessel having a lid adapted to be closed during the degreasing treatment, and to be opened before and after such treatment to permit access to the said articles, which process comprises heating the solvent and causing a portion of the warm vapour to condense on the surface of the cold articles and to dissolve the grease therefrom, allowing the condensed solvent and grease dissolved therein to drain away from the articles before removing the same from the vessel, and condensing vapor inside said vessel during and after degreasing by supplying cooling fluid to conduits inside the degreasing vessel.

JOSEPH SAVAGE. 

